Intensity and colour of artificial light at night affect insect attraction in a taxon‐dependent manner

Artificial illumination at night is an anthropogenic disturbance which severely impacts our societies and ecosystems. Nocturnal insects are crucial ecosystem service providers and their fitness can be greatly affected by anthropogenic light at night, among others via positive phototaxis.

The rising popularity and efficiency of light emission diode (LED) lighting technology accentuate the need to understand how both spectrum and intensity affect insect behaviour, especially when building spectrally tuneable lighting systems to mitigate the impact of light pollution.

We measured the phototactic responses of insects of different taxa to artificial light at night using LED traps emitting light at four narrowband wavelengths of three intensities over 11 nights at two locations in natural forested areas in the Netherlands.

We found that different light colours elicit order‐specific phototactic responses. For example, Diptera were strongly attracted towards green and blue light, while moth species displayed phototactic responses mostly towards ultraviolet emissions. In addition, increased intensity levels positively affected the strength of attraction, irrespective of light colour.

Finally, our approach enabled us to calculate spectral sensitivity curves to compare spectral phototaxis responses between insect orders. Although there is no ‘one size fits all’ solution, we conclude that mitigation of light pollution affecting insect attraction can be best achieved by using longer wavelengths of low light intensity.